1. Field
Exemplary embodiments of the present invention relate to a semiconductor designing technology, and more particularly, to a line driving method of a semiconductor device.
2. Description of the Related Art
Most semiconductor memory devices including Dynamic Random Access Memory (DRAM) devices are using a row/column addressing scheme to access a particular memory cell. First, a semiconductor memory device receives a row address from the outside to select a row, which is a word line, and then receives a column address inputted from the outside to select one column in the selected row, which is a bit line.
In order to select one row, word lines have to be driven, and a column selection line has to be driven as well to select one column. The column selection line is a line for transferring a column selection signal that is selectively enabled by decoding the column address in a column decoder. The column selection signal is a control signal of a switch that selectively connects a local data bus and a bit line during a read operation or a write operation. While the column selection signal pulses, data are exchanged between a corresponding bit line and a corresponding local data bus.
As semiconductor memory devices are integrated higher and higher, more load is applied to the column selection line. Since the column selection line is a relatively long line among the lines disposed in a core region of a semiconductor memory device, the load of the line to be driven is not small.
In order to drive a line with much load, a driving circuit is required to have a sufficient driving force. When the driving circuit has a small driving force, a signal transfer rate through the line is dramatically decreased, which is problematic.
A transistor that constitutes the driving circuit has to be designed large to have the sufficient driving force. However, the size of the transistor cannot be enlarged without any definite plan, because the circuit area and current consumption have to be taken into consideration. Therefore, the insufficient driving force of the driving circuit has to be complemented while designing the transistor of the driving circuit in an appropriate size. Two methods have been suggested to complement the driving force of the driving circuit for a line with much load.
One is to insert a repeater in the middle of the line, and the other is to boost the line by generating a control signal. The insertion of a repeater into the middle of the line may cause another problem. Particularly, it takes a dummy cell array and a sense amplifier array to insert a repeater into the column selection line in a DRAM device having an open bit line structure. Since the dummy cell array and the dummy sense amplifier array occupy a great area, it is disadvantageous in terms of the chip size. Also, the method of boosting the line by generating a control signal not only has difficulty in controlling timing but also has increased current consumption.
These are not the only problems of the driving circuit of the column selection line, but also the problems of multiple lines having much load, such as word lines.